diff options
Diffstat (limited to 'roms/u-boot/drivers/serial/serial_bcm283x_mu.c')
| -rw-r--r-- | roms/u-boot/drivers/serial/serial_bcm283x_mu.c | 204 |
1 files changed, 204 insertions, 0 deletions
diff --git a/roms/u-boot/drivers/serial/serial_bcm283x_mu.c b/roms/u-boot/drivers/serial/serial_bcm283x_mu.c new file mode 100644 index 000000000..58fa722b4 --- /dev/null +++ b/roms/u-boot/drivers/serial/serial_bcm283x_mu.c @@ -0,0 +1,204 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org> + * + * Derived from pl01x code: + * + * (C) Copyright 2000 + * Rob Taylor, Flying Pig Systems. robt@flyingpig.com. + * + * (C) Copyright 2004 + * ARM Ltd. + * Philippe Robin, <philippe.robin@arm.com> + */ + +/* Simple U-Boot driver for the BCM283x mini UART */ + +#include <common.h> +#include <dm.h> +#include <errno.h> +#include <watchdog.h> +#include <asm/gpio.h> +#include <asm/io.h> +#include <serial.h> +#include <dm/platform_data/serial_bcm283x_mu.h> +#include <dm/pinctrl.h> +#include <linux/bitops.h> +#include <linux/compiler.h> + +struct bcm283x_mu_regs { + u32 io; + u32 iir; + u32 ier; + u32 lcr; + u32 mcr; + u32 lsr; + u32 msr; + u32 scratch; + u32 cntl; + u32 stat; + u32 baud; +}; + +#define BCM283X_MU_LCR_DATA_SIZE_8 3 + +#define BCM283X_MU_LSR_TX_IDLE BIT(6) +/* This actually means not full, but is named not empty in the docs */ +#define BCM283X_MU_LSR_TX_EMPTY BIT(5) +#define BCM283X_MU_LSR_RX_READY BIT(0) + +struct bcm283x_mu_priv { + struct bcm283x_mu_regs *regs; +}; + +static int bcm283x_mu_serial_getc(struct udevice *dev); + +static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate) +{ + struct bcm283x_mu_serial_plat *plat = dev_get_plat(dev); + struct bcm283x_mu_priv *priv = dev_get_priv(dev); + struct bcm283x_mu_regs *regs = priv->regs; + u32 divider; + + if (plat->skip_init) + goto out; + + divider = plat->clock / (baudrate * 8); + + writel(BCM283X_MU_LCR_DATA_SIZE_8, ®s->lcr); + writel(divider - 1, ®s->baud); + +out: + /* Flush the RX queue - all data in there is bogus */ + while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ; + + return 0; +} + +static int bcm283x_mu_serial_getc(struct udevice *dev) +{ + struct bcm283x_mu_priv *priv = dev_get_priv(dev); + struct bcm283x_mu_regs *regs = priv->regs; + u32 data; + + /* Wait until there is data in the FIFO */ + if (!(readl(®s->lsr) & BCM283X_MU_LSR_RX_READY)) + return -EAGAIN; + + data = readl(®s->io); + + return (int)data; +} + +static int bcm283x_mu_serial_putc(struct udevice *dev, const char data) +{ + struct bcm283x_mu_priv *priv = dev_get_priv(dev); + struct bcm283x_mu_regs *regs = priv->regs; + + /* Wait until there is space in the FIFO */ + if (!(readl(®s->lsr) & BCM283X_MU_LSR_TX_EMPTY)) + return -EAGAIN; + + /* Send the character */ + writel(data, ®s->io); + + return 0; +} + +static int bcm283x_mu_serial_pending(struct udevice *dev, bool input) +{ + struct bcm283x_mu_priv *priv = dev_get_priv(dev); + struct bcm283x_mu_regs *regs = priv->regs; + unsigned int lsr; + + lsr = readl(®s->lsr); + + if (input) { + WATCHDOG_RESET(); + return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0; + } else { + return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1; + } +} + +static const struct dm_serial_ops bcm283x_mu_serial_ops = { + .putc = bcm283x_mu_serial_putc, + .pending = bcm283x_mu_serial_pending, + .getc = bcm283x_mu_serial_getc, + .setbrg = bcm283x_mu_serial_setbrg, +}; + +#if CONFIG_IS_ENABLED(OF_CONTROL) +static const struct udevice_id bcm283x_mu_serial_id[] = { + {.compatible = "brcm,bcm2835-aux-uart"}, + {} +}; + +/* + * Check if this serial device is muxed + * + * The serial device will only work properly if it has been muxed to the serial + * pins by firmware. Check whether that happened here. + * + * @return true if serial device is muxed, false if not + */ +static bool bcm283x_is_serial_muxed(void) +{ + int serial_gpio = 15; + struct udevice *dev; + + if (uclass_first_device(UCLASS_PINCTRL, &dev) || !dev) + return false; + + if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5) + return false; + + return true; +} + +static int bcm283x_mu_serial_probe(struct udevice *dev) +{ + struct bcm283x_mu_serial_plat *plat = dev_get_plat(dev); + struct bcm283x_mu_priv *priv = dev_get_priv(dev); + fdt_addr_t addr; + + /* Don't spawn the device if it's not muxed */ + if (!bcm283x_is_serial_muxed()) + return -ENODEV; + + /* + * Read the ofdata here rather than in an of_to_plat() method + * since we need the soc simple-bus to be probed so that the 'ranges' + * property is used. + */ + addr = dev_read_addr(dev); + if (addr == FDT_ADDR_T_NONE) + return -EINVAL; + + plat->base = addr; + plat->clock = dev_read_u32_default(dev, "clock", 1); + + /* + * TODO: Reinitialization doesn't always work for now, just skip + * init always - we know we're already initialized + */ + plat->skip_init = true; + + priv->regs = (struct bcm283x_mu_regs *)plat->base; + + return 0; +} +#endif + +U_BOOT_DRIVER(serial_bcm283x_mu) = { + .name = "serial_bcm283x_mu", + .id = UCLASS_SERIAL, + .of_match = of_match_ptr(bcm283x_mu_serial_id), + .plat_auto = sizeof(struct bcm283x_mu_serial_plat), + .probe = bcm283x_mu_serial_probe, + .ops = &bcm283x_mu_serial_ops, +#if !CONFIG_IS_ENABLED(OF_CONTROL) || CONFIG_IS_ENABLED(OF_BOARD) + .flags = DM_FLAG_PRE_RELOC, +#endif + .priv_auto = sizeof(struct bcm283x_mu_priv), +}; |